21519728 has 20 divisors (see below), whose sum is σ = 41771880. Its totient is φ = 10739904.

The previous prime is 21519727. The next prime is 21519791. The reversal of 21519728 is 82791512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21519721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11738 + ... + 13446.

It is an arithmetic number, because the mean of its divisors is an integer number (2088594).

Almost surely, 2^21519728 is an apocalyptic number.

It is an amenable number.

21519728 is a deficient number, since it is larger than the sum of its proper divisors (20252152).

21519728 is a wasteful number, since it uses less digits than its factorization.

21519728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2504 (or 2498 counting only the distinct ones).

The product of its digits is 10080, while the sum is 35.

The square root of 21519728 is about 4638.9360849229. The cubic root of 21519728 is about 278.1499113822.

The spelling of 21519728 in words is "twenty-one million, five hundred nineteen thousand, seven hundred twenty-eight".